Isurus is a genus of mackerel sharks in the family Lamnidae, commonly known as the mako sharks. The two living species are the common shortfin mako shark (I. oxyrinchus) and the rare longfin mako shark (I. paucus). They range in length from 2.5 to 4.5 m (8.2 to 14.8 ft), and have an approximate maximum weight of 800 kg (1,800 lb). Several extinct species are known from fossils found in sediments from Cretaceous to Quaternary (age range: 99.7 to 0.781 million years ago).